public class test02 {
    public String toLowerCase(String s) {
        StringBuilder stringBuilder = new StringBuilder();
        for(int i = 0; i < s.length(); i++){
            char ch = s.charAt(i);
            if(ch >= 'A' && ch <= 'Z'){
                ch += 32;
                stringBuilder.append(ch);
            }else{
                stringBuilder.append(ch);
            }
        }
        return stringBuilder.toString();
    }

    public static void main(String[] args) {

    }
}
